The invention relates to a method for controlling rock drilling.
wherein a pressure liquid operated percussion device belonging to a rock drill machine delivers stress waves to rock through a tool; wherein the rock drill machine and the tool are simultaneously pushed against the rock by means of a feed motor, and the tool is simultaneously rotated by means of a rotation motor;
the method comprising:
determining the maximum feed force;
supplying pressure liquid to the feed motor along a feed pressure channel and away from the feed motor along a return channel;
supplying pressure liquid to the percussion device along a percussion device pressure channel and away from the percussion device along a return channel;
supplying pressure liquid to the rotation motor (8) along a rotation motor pressure channel and away from the rotation motor (8) along a return channel;
controlling the feed force in relation to the feed speed so that when the feed speed is increased the feed force is decreased and vice versa; and
controlling the feed force in relation to the rotation torque so that when the rotation torque is increased the feed force is decreased and vice versa.
Further the invention relates to an apparatus for controlling rock drilling with a pressure liquid operated rock drilling machine, a drilling tool being attachable to the rock drilling machine,
a percussion device) for creating stress waves to the tool,
a percussion pressure channel and a percussion return channel (46) for supplying pressure liquid to the percussion device and away
a rotation motor for rotating the tool, a rotation pressure channel and a rotation return channel for supplying pressure liquid to the rotation motor and away,
a feed motor for feeding the rock drilling machine to the drilling direction and to reverse direction,
a feed pressure channel and a feed return channel for supplying pressure liquid to the feed motor and away,
a feed control valve for controlling the supply of the pressure liquid to the feed motor,
a rotation control valve for controlling the supply of the pressure liquid to the rotation motor,
a percussion control valve for controlling the supply of the pressure liquid to the percussion device,
measuring equipment
for measuring the feed speed and/or the feed position and to measure the pressure of the pressure liquid supplied to the feed motor and
for measuring the pressure of the pressure liquid supplied to the rotation motor, and
a control unit (30), to which the measuring equipment is connected and which is connected to control the feed control valve, the rotation control valve and the percussion control valve on the basis of the measured values.
When holes are drilled into rock, the drilling conditions may vary in several ways. The rock may include voids and cracks, and rock layers having different hardness, which is why drilling parameters should be adjusted according to the drilling conditions.
Conventionally, an operator controls the operation of a rock drill on the basis of his or her personal experience. The operator sets certain drilling parameters on the basis of the presumed rock characteristics. During drilling, the operator checks the rotation and monitors the progress of the drilling. When necessary, he changes the feed force and/or the percussion power of the percussion device to suit a particular type of rock, thus trying to achieve a fast but still smooth drilling process. In practice, the operator is able to adjust only one drilling parameter and control its influence on the drilling process in several seconds or tens of seconds. When the quality of rock or the drilling characteristics thereof changes rapidly, even a qualified operator cannot adapt the drilling parameters quickly enough to suit the rock. It is thus obvious that the operator cannot ensure a good tool life if drilling conditions vary rapidly. Furthermore, it is practically impossible even for a qualified operator to monitor and control the operation of the rock drilling machine during an entire working shift such that the drilling progresses efficiently at every moment, simultaneously taking into account the stresses the tool is subjected to.
Also in the down hole drilling there may exist an uncontrolled rush of the rock drill, when the force of the stone resisting the feed suddenly disappears for instance when the drill bit hits a hole in the rock. Further in this kind of drilling the hydraulics as such easily vibrates or oscillates which creates problems for the drilling control.
Typically in this kind of drilling equipment the feed channels are equipped with counterbalance valve. The purpose of the counterbalance valve is to prevent unwanted movement of the rock drill by closing the return channel if there is no control signal or control pressure, which would open the counterbalance valve.